Process of preparing dry carbon dioxide



Oct. 16, 1 934. R. T. HOWES 1,977,063

PROCESS OF PREPARING DRY CARBON DIOXIDE Filed Nov. 18, 1950 PatentedOct. 16, 1934 warren STATES PROCESS OF PREPARING DRY CARBON DIOXIDERaymond Thayer Howes, Long Beach, Calif assignor, by mesne assignments,to Hewhngs Mumper and Lewis Cruickshank, Los Angeles,

Calif.

Application November 18, 1930, Serial No. 496,416

4 Claims.

This invention relates to a process and apparatus for the manufacture orcarbon dioxide gas and is especially applicable to its recovery in asubstantially anhydrous form.

The principal object of the invention is to provide a means in themanufacture of carbon dioxide, wherein steam is a factor, for thecomplete separation or" steam, or water vapor, from carbon dioxide gaswhereby the latter is recovered in a pure anhydrous condition.

The invention is also directed to an improvement on the co-pendingapplications of Norris Goodwin, Serial No. 405,048, filed November 5,1929, and Serial No. 450,155, filed May 6, 1930.

By referring to the drawing, wherein Fig. 1 is an elevation, partly insection, and- Fig. 2 shows a manifolding arrangement, and as shown insaid co-pending applications, an autoclave 10 is filled to apredetermined level with a mixture of a magnesium carbonate and silica,said mixture being formed as a slurry of the finely ground materials andwater.

A steam spray pipe 11 is adapted to agitate the slurry in autoclave 10while holding the autoclave under a pressure running as high as 500pounds per square inch, or more, and at a corresponding temperature.Such pressure is held by a valve 12 in a gas discharge pipe 13 which isconnected to the upper part of a steam condenser 14 of a well knowntype, having a plurality of tubes 15 for the passage of gases and adischarge head 16 suitably jacketed at 17 to permit the flow of coolingwater from supply 18 to pass therearound and fiow through pipe 19 andaround tubes 15. Valve 12 is adapted to be suitably connected in a wellknown manner with one, or more, containers 20 for dry carbon dioxide gasthrough a pipe 21, and a pipe 22 connects autoclave 10 with the lowerpart of condenser 14.

A conduit 24, controlled by valve 25, is provided for the discharge ofthe treated material from autoclave 10, and discharge head 16, whichforms a reflux condenser section, is provided with a perforated circularplate supporting a bi-metallic thermostat 27 (or other equivalent heatresponsive device) which actuates a valve 28 adapted to open and closean orifice 29 placed in an otherwise tight closing plate 30. Thethermostat 27 is placed in reflux condenser 16 at a critical pointtherein, that is, a point where normally said condenser would have allthe water condensed out of the passing gas at a given rate of flow, thepassage of gas containing steam causing thermostat 27 and valve 28 toclose orifice 29.

In this manner it will be seen that a control, distant from theactuating thermostat, is provided whereby the passage of steam intocontainer 20 is prevented.

The operation is as follows:

Autoclave 10 being supplied with the slurry containing the raw material,which, may be pumped in through conduit 24, valves 12, 23a, and 25 areclosed and steam at the desired temperature is admitted through pipe 11until a desired pressure is reached and CO2 is started to be evolved.Valve 23 is thenopened and valve 121s opened sufliciently only. to-maintain the desired pressure and steam and carbon dioxide gas willcommence to pass into condenser 14 The reaction in autoclave 10isaccording to the equation,-

MgCO3+SiO2- magnesium silicate-l-COz The exact formula for the magnesiumsilicate is unknown at present, but the reaction is complete from leftto right to provide a magnesium silicate having valuable bleaching andother properties.

The steam and CO2 pass into condenser 14 and thence the pure CO2 passesthrough head 16 and pipe 21 into container 20, there being maintained atemperature differential whereby all the steam is condensed in condenser14 and below the critical point of head 16 by the reduction oftemperature provided by the cooling water, the condensed steam beingcontinuously withdrawn through pipe 26.

The rate of flow is governed by the thermostat 27 which serves to openor close the valve 28 in proportion to the increase or decrease oftemperature in head 16 at the critical point therein, to the end that inthe upper part of head 16 there is nothing but anhydrous carbon dioxidegas, which passes under autogenous pressure to fill container 20.

Such filling will continue until a desired pressure has been reached incontainer 20 when the stream of gas may be diverted to another similarcontainer, it being understood that a pressure difierential ismaintained between container 20 and pipe 13.

The carbon dioxide gas thus obtained is in a pure state and suitable forthe manufacture of dry ice and other uses.

Upon the completion of the reaction in autoclave 10, the valve 12 may beclosed and the 11.

magnesium silicate thereby forced out through conduit 24 for use invarious arts.

It is to be understood that there are many different ways of producing amixture of carbon dioxide and Water vapor up to the temperature of steamfor which the described apparatus can be used to good efiect, it beingdesirable to so arrange the condenser that sufiicient length of refluxcondenser be provided to condense out all the water vapor by using lowenough tempera tures in the cooling water. The position of plate 30 isapproximately illustrated and preferably forms a discharge point fromportion 16 which may, or may not, be subject to any artificial cooling.

I claim as my invention:

1. A process of producing dry carbon dioxide which comprises: treating amixture or magnesium carbonate and silica under superatmosphericpressure with steam to produce a mixture of carbon dioxide and steam,passing a stream of said mixture into a zone of condensation whereincomplete separation of water vapor from the carbon dioxide is normallyeffected, and permitting the carbon dioxide to flow from said zone whilethe temperature in said zone is at or below a point at which the watervapor is substantially completely separated, and preventing the flow ofcarbon dioxide from said zone if the temperature rises above said point.

2. A process of producing dry carbon dioxide which comprises: treating amixture of magnesium carbonate and silica under superatmosphericpressure with steam to produce a mixture or" carbon dioxide and steam,passing a stream of said mixture 'into a zone of condensation whereincomplete separation of water vapor from the carbon dioxide is normallyeffected, and permitting the carbon dioxide to flow from said zone whilethe temperature at a critical point in said zone is at or below a pointat which the water vapor is substantially completely separated, andpreventing the flow of carbon dioxide from said zone if the temperaturerises above said point.

3. A process of producing dry carbon dioxide .which comprises: treatinga mixture of magnesium carbonate and silica under super atmosphericpressure with steam to produce a mixture of carbon dioxide and steam,passing a stream of said mixture into a zone of condensation whereincomplete separation of water vapor from the carbon dioxide is normallyeirected under superatmospheric pressure, and permitting the carbondioxide to flow from said zone while the temperature in said zone is ator below a point at which the water vapor is substantially completelyseparated, and preventing the flow of carbon dioxide from said zone ifthe temperature rises above said point.

4. A process of producing dry carbon dioxide which comprises: treating amixture of magnesium carbonate and silica under superatmosphericpressure with steam to produce a mixture of carbon dioxide and steam,passing a stream of said mixture into a zone of condensation whereincomplete separation of water vapor from the carbon dioxide is normallyeiiected, and permitting the carbon dioxide to flow from said zone whilethe temperature at a critical point in said zone is at or below a pointat which the water vapor is substantially completely separated, andpreventing the flow of carbon dioxide from said zone ii the temperaturerises above said point: such control being efifective at a place in saidzone more distant from the place of origin of said mixture than saidcritical point.

RAYMOND THAYER HOWES.

